Covalent organic frameworks derived F/N co-doped porous carbon for potassium-ion batteries

Heteroatom-doped porous carbon derived from covalent organic frameworks (COFs) is of great interest due to their unique nanostructure and ability to host a large ionic radius of K+. Herein, we reported F and N co-doped porous carbon (FNC) anode for potassium ion batteries (PIBs) for the first time by carbonized rational design COFs. The synthesized FNC retains characteristics of COFs such as a nanosheet structure, rich hierarchical pores, and large interlayer spacing, which facilitate K+ diffusion. Besides, generated abundant defects provide active sites for K+ storage. The specific introduction of F and N by COFs molecules enables the formation of conjugation effect (Π78, Π67), stable C-F bonds and -C-F…N- interactions in carbon layers, improving the electrical conductivity and structural stability of FNC. As a result, the FNC anode shows a high reversible specific capacity of 292 mAh g−1 at 50 mA g−1 as well as excellent cyclability of 118 mAh g−1 at 1000 mA g−1 over 200 cycles. This work will serve as a guide for the synthesis of heteroatom co-doped porous carbon materials for high-performance potassium-ion storage.